1. Field of the Invention
The present invention relates generally to interface devices between humans and computers, and more particularly to computer interface devices that provide force feedback to the user.
2. Description of the Prior Art
Virtual reality computer systems provide users with the illusion that they are part of a “virtual” environment. A virtual reality system will typically include a computer processor, virtual reality software, and virtual reality I/O devices such as head mounted displays, sensor gloves, three dimensional (“3D”) pointers, etc.
Virtual reality computer systems may be used for training. In many fields, such as aviation and vehicle and systems operation, virtual reality systems have been used successfully to allow a user to learn from and experience a realistic “virtual” environment. The appeal of using virtual reality computer systems for training relates, in part, to the ability of such systems to allow trainees the luxury of confidently operating in a highly realistic environment and making mistakes without “real world” consequences. For example, a virtual reality computer system allows a doctor-trainee or other human operator or user to “manipulate” a scalpel or probe within a computer-simulated “body,” and thereby perform medical procedures on a virtual patient. In this instance, the I/O device, which is typically a 3D pointer, stylus, or the like, is used to represent a surgical instrument such as a scalpel or probe. As the “scalpel” or “probe” moves within a provided space or structure, results of such movement are updated and displayed in a body image displayed on the screen of the computer system so that the operator gains the experience of performing such a procedure without practicing on an actual human being or a cadaver. In other applications, virtual reality computer systems allow a user to handle and manipulate the controls of complicated and expensive vehicles and machinery for training and/or entertainment purposes.
For virtual reality systems to provide a realistic (and therefore effective) experience for the user, sensory feedback and manual interaction should be as natural as possible. In addition to sensing and tracking a user's manual activity and feeding such information to the controlling computer to provide a 3D visual representation to the user, a human interface mechanism should also provide force or tactile (“haptic”) feedback to the user. The need for the user to obtain realistic haptic information is extensive in many kinds of simulation and other applications. For example, in medical/surgical simulations, the “feel” of a probe or scalpel simulator is important as the probe is moved within the simulated body. It would beinvaluable to a medical trainee to learn how an instrument moves within a body, how much force is required depending on the operation performed, the space available in a body to manipulate an instrument, etc. Other applications similarly benefit from the realism provided by haptic feedback. A “high bandwidth” interface system, which is an interface that accurately responds to signals having fast changes and a broad range of frequencies as well as providing such signals accurately to a control system, is therefore desirable in these and other applications.
Several existing devices provide multiple degrees of freedom of motion of an instrument or manipulatable object and include haptic feedback. Many of these devices, however, are limited in how many degrees of freedom that forces are provided, and may also be less accurate and realistic than desired for a particular application. Devices having greater realism yet reasonable cost are desired for medical and other virtual simulation applications.